Support wire for dandy roll covers



Feb. 20, 1962 P. s. SINCLAIR SUPPORT WIRE FOR DANDY ROLL COVERS Filed Sept. 28, 1959 /2 20 l2 l3 /2 20 Q J INVENTOR. PTE SINCLAIR BY ATTOENflYS 3,621,590 Er? FGR DANDY RGLL CQVERS Peter S. Sinclair, South Hadley, Mass, assignor to The Sinclair Company, Holyoke, Mass, a corporation of Massachusetts Filed Sept. 28, 1959, Ser. No. 842,669 2 Claims; (Cl. 29-121) port wire runs between adjacent parallel wires of the.

woven cover. The support wire and parallel wires of the wire cover form small pockets susceptible of clogging by the buildup of clay or filler. Numerous solutions have been devised to overcome this problem, without complete success.

One solution involves the positioning of the wire cloth at an angle to the support wires. However, the seam which joins the opposite ends of the cover is of spiral configuration, not parallel to the dandy roll axis. Since it is desirable, particularly from the standpoint of manufacturing costs, to have a seam of as short a length as possible, this solution is not entirely acceptable. Another solution to the problem involves the disposition of a support wire in spiral fashion around the dandy roll. The advantages of this solution are limited, since providing a sufliciently large angle between the support wire and wires of the cover, results in the spiral support wire having too large a pitch for adequately supporting the wire cover.

The principal object of this invention is to provide improved means for supporting dandy roll covers which substantially eliminates the tendency of the wire mesh to become clogged with deposits of clay or filler from the fluent pulp.

Another object of this invention is to provide an improved support wire for dandy roll covers having a configuration which agitates or creates a turbulence in the fluent pulp when the dandy roll is rotated upon a Fourrinier wire, thereby keeping the covers clean and reducing the amount of water thrown out of roll by centriiugal force.

A further object of this invention is to provide improved means for supporting the wire mesh cover of a high speed dandy roll.

The above and other objects of this invention will be apparent from the following description and with reference to the accompanying drawing in which:

FIG. 1 is a partial perspective view of a dandy roll embodying this invention;

FIG. 2 is a cross sectional view on an enlarged scale of the winding or support wire of FIG. 1;

FIG. 3 is a diagrammatical showing of a dandy roll embodying the invention;

FIG. 4 is a diagrammatical showing of a dandy roll embodying a modified form of the invention; and

FIG. 5 is a diagram showing the relationship of the support wire and dandy roll cover.

Referring in detail to the drawing, a portion of a dandy roll is shown in FIG. 1. The dandy roll support structure is of conventional construction and comprises a plurality of circumferentially spaced support members or top rods 6 disposed parallel to the axis of the dandy roll. A wire cloth or mesh cover 8 is disposed around the circumference of the roll and its opposed edges are joined together by a seam 10, FIG. 3. The seam 10 is disposed parallel to the roll axis. The wire cloth cover is of the woven type formed of warp and weft wires. Wires 11 run parallel to the roll axis and wires 13 run around the roll in planes perpendicular to the roll axis. Ease of manufacture and economy make it desirable to position the cover on the roll in the manner shown and to form the seam parallel to the roll axis.

Underlying the wire cloth 8 and supporting it in radially spaced relation to the top rods is a winding or support wire which is in the form of a continuous length of metal ribbon mounted edgewise on the top rods. The ribbon 12 extends around the roll in a continuous spiral from one end of the roll to the other. The ends of the ribbon may be secured to'heads 15 of the roll. The ribbon 12 is of generally rectangular cross section having a squared inner edge 14, FIG. 2, fitted into outwardly opening, axially spaced slots 16 in the top rods 6. The. outer edge of-the ribbon is rounded or convexly curved permitting relatively free flow of fluid through the cover 8 and around the ribbon when the dandy roll is in oper-- ation pressing a fluent paper pulp carried by a Fourdrinier wire. The curved outer surface of the ribbon 12 tangentially engages the undersurface of the wire cover 8 providing minimum area of contact between the support ribbon and cover. This construction substantially reduces the tendency of the cover to pick up clay and pulp deposits which clog the dandy roll.

As best seen in FIG. 3, the spiral formed by the winding of the ribbon 12 around the dandy roll has suflicient pitch so that the ribbon traverses below the wires 13 at a relatively large angle. This angle, indicated at a in FIG. 3, is selected to permit substantially unobstructed fluid flow through the cover 8. This relationship reduces to a minimum the size of the pockets formed by adjacent parallel wires l3 and the upper surface of the winding wire disposed between the adjacent wires.

As best seen in FIG. 2, the inner portion of the ribbon 12 extends radially outward of the top rods 6. The outer portion of the ribbon is deformed or crimped in a zigzag pattern having portions 19 which extend alternately to one side and the other of the plane of the uncleformed inner portion of the ribbon. By referring to FIG. 5, it can be seen that the crimped zigzag edge portions of the ribbon are disposed at a relatively large angle b to the wires 13 of the cover 8. The relatively sharp angle of traverse of the crimped portions of the ribbon 12 to the wires 13 of the cover further acts to minimize the size of the pockets between adjacent parallel wires 13 and the underlying portions of the support wire.

The crimped outer portions of the ribbon 12, forming the zigzag pattern, are of rectilinear configuration. Thus, as the dandy roll is rotated, the ribbon agitates or creates a turbulence in the water of the fluent pulp carried between adjacent coils of the ribbon. This agitation of the fluent pulp substantially prevents the undesirable buildup of clay deposits in the mesh of the cover and makes feasible higher speed dandy roll operation without the problem of screen clogging.

The zigzag configuration of the support ribbon also solves a problem known as water throwing which is the projection of water out of the upper portion of the dandy roll by centrifugal force as the roll is rotated. Water throwing often results in staining or spotting of the paper web. Applicants zigzag support ribbon imparts lateral components of motion to the water carried between adjacent coils of the ribbon and results in a substantial reduction in the amount of water throwing.

A modified form of this invention is shown in FIG. 4 and comprises a first metal ribbon 12 disposed around the dandy roll in a spiral as described above and shown in FIG. 3. The pitch of the spiral is selected for minimum obstruction of fluid flow through the cover. This minimum obstruction is achieved when the ribbon forms the relatively large angle a to the wires 13 of the cover. While the angle a is made sufficiently large to permit substantially unobstructed flow through the cover, in certain instances it has been found that the coils of the ribbon 12 are too widely spaced apart for adequately supporting the wire screen throughout its length. In the modified form of this invention, as shown in FIG. 4, a second continuous metal ribbon 2% identical to the ribbon 12, is wound around the roll in a spiral intermediate the coils of the first ribbon 12. The ribbon 29 is wound in a spiral having a pitch equal to that of the first ribbon 12. The ribbon 12 is thus also disposed at an angle a to the wires 13 of the cover. While the pair of support ribbons 12 and 20 are spaced closely enough to provide adequate support for the Wire cover, they retain the advantage of a support wire wound in a spiral of relatively large pitch.

Having thus described this invention, what is claimed is:

1. In a dandy roll having axially extending, circumferentially spaced support rods and a woven wire cover disposed around said roll; means for supporting said cover in spaced relation to the support rods comprising a metallic ribbon mounted in edgewise relation on said support rods, said ribbon being wound in a continuous spiral around the roll and being of generally rectangular and uniform cross sectional size throughout its length so that the ribbon is of generally equal magnitude from its inner to outer edge, the outer edge of said ribbon being of convex curvature in tangential contact with the undersurface of said cover, the outer edge portion of said ribbon having a zig-zag configuration throughout its length. i

2. In a dandy roll having axially extending, circumferentially spaced support rods and a woven wire cover disposed around said roll with opposed edges of said cover joined by a seam parallel to the roll axis, said cover including wires extending around said roll; means for proximately equal to one-half said pitch, said metallic,

ribbons being of generally rectangular and uniform cross sectional size throughout their length, the outer edge of said ribbons being of convex curvature in tangential con tact with the outer surface of said cover, the outer edgeportions of said ribbons being of zig-zag configuration.

References Cited in the file of this patent UNITED STATES PATENTS 2,803,172 Trotman Aug. 20, 1957 

